The invention regards a valve arrangement for reciprocating machinery such as a pump and a compressor.
Reciprocating machinery, or a reciprocating engine, typically has an induction valve and an exhaust valve, hereinafter termed in-valve and out-valve, for each piston. Normally, springloaded one-way valves are used, where a spring closes the valve by forcing a valve body against a valve seat. A valve may be opened for flow either through mechanical action or by pressure in the working medium of the reciprocating engine, hereinafter termed fluid, acting on the valve body to generate a force directed opposite to the force from said spring.
If valves of the type in question are arranged so that the direction of flow through the valves is parallel with the cylinder axis of the reciprocating engine, the valves and attached pipework project a relatively long way from the cylinder head of the reciprocating engine. Therefore it is desirable to mount the valves in a manner such that fluid may flow across the cylinder axis immediately outside the cylinder head. If fluid is to flow to and from the cylinder in parallel with the cylinder axis, the direction of fluid flow must change in connection with the valve arrangement. Such a change in direction results in lateral flow forces that act on the valve body and cause misalignment of this. The result is skewed or uneven wear on the valve body and the valve seat, which causes leakage in a closed valve. In the event of such leakage the valve in question must be replaced, or the valve must be disassembled and the worn parts replaced. Changing valves or worn valve components may be time consuming, particularly in the case of large reciprocating machinery such as a reciprocating pump for drill fluid for use in drilling of petroleum wells.